ODS solidly wears a 5 1/2. Usually, I just order up from last summer’s Keen H2 and it fits. Last year, he wore a size 5. This year, the 6 is too large but the 5 is a little too tight. His sneakers (Merrill and Geox) are 5 1/2. He tried the Geox sandal (Kyle). It it didn’t fit because he has a narrow heel. Any suggestions for shoes similar to Keen H2? Thank you.